The expressiveness of DAC

We define a new logic-based query language, called DAC, which is an extension of Datalog. A DAC(w(n),h(n))(b(n))-program consists of a family of Datalog programs P n such that w(n),h(n),b(n) bound the width of rules, the number of rules, and the recursion depth of any P n , respectively. We exhibit queries which are not Datalog expressible but are DAC expressible. We also prove non-expressiveness results for DAC and we infer various strict hierarchies obtained by allowing more rapidly growing functions on the bound parameters.